1. Field of the Invention
The present invention relates to a an auxiliary shielding device for an electrical connector, and particularly to an auxiliary shielding device which reduces the effect of EMI acting on a connector.
2. The Prior Art
A connector is equipped with an EMI shield to ensure noise-free signal transmission between a computer system and peripherals, such as a mouse, keyboard, and printer. Since the connector is used to integrate different input/output functions, the requirements for stable signal transmission are high. Accordingly, the connector is completely enclosed by the EMI shield.
FIG. 1 shows a conventional connector 5 which is enclosed by a shield on five surfaces. A shielding face 50 which encloses a mating face of the connector 5 is defined with an opening 501 providing an engagement between the shield and the connector 5. The shield further includes grounding legs 51 for establishing a grounding path to a computer housing. As computers become increasingly more complex, many devices require assembly within a limited space. Accordingly, interference between transmission lines thereof increases. Thus, the shield and grounding legs 51 should be adapted to reduce noise or interference, however, the result has been unsatisfactory especially for high frequency signal transmission.
As seen in FIG. 2, interference may result from the installation arrangement between the connector 5 and the computer housing 6. When the connector 5 is assembled to the housing 6, a gap (t) exists therebetween and a portion of the shielding face 50 is exposed to the gap (t) before a mating connector is assembled thereto. Accordingly, EMI through the gap (t) may affect signal transmission.
A connector 7 as shown in FIG. 3 introduces an improvement to address the conventional problem. A shield 71 assembled to the connector 7 forms a first plate 712 and a second plate 713 both outwardly extending from a receptacle 711. Both first and second plates 712, 713 are integrally formed with the shield 71 and tightly clip with an inserted mating connector thereby providing satisfactory EMI protection. However, both plates 712, 713 are integrally formed with the shield resulting in poor resiliency thereof. In addition, a gap may still exist between the plates 712, 713 and a computer enclosure. Consequently, noise is not effectively reduced. Furthermore, such a configuration is not conducive to mass production.
Hence, an improved shielding device is requisite to overcome the disadvantages of the prior art.